1. Technical Field
The present invention relates to a fractal structure that controls electromagnetic waves of wavelengths ranging from visible light to microwaves, particularly to localize and confine electromagnetic waves of a particular wavelength in the fractal structure as well as absorbing without reflection, storing, amplifying and filtering the electromagnetic waves, a method for manufacturing the same and applications thereof.
2. Background Art
Since the 1990s, vigorous efforts have been made in theoretical research into the reflection and transmission of electromagnetic waves by fractal structures characterized by so-called self-similarity, which means that any part of the structure is similar to the entire structure. There has been the remarkable discovery that reflection coefficients become higher in a particular direction, or change significantly in a periodic manner, with the wall thickness of the fractal structure or with the frequency [Non-Patent Documents 1, 2]. However, theoretical calculations have been limited mostly to simple structures such as the Cantor set having a fractal dimension, which represents the complexity of a fractal structure, of 0.6309. Experimental researches, on the other hand, are few and are directed toward two-dimensional fractal structures [Non-Patent Document 3], and have not been made for three-dimensional fractal structures due to the difficulty of fabricating complicated fractal structures.
To control electromagnetic waves of wavelengths ranging from visible light to microwave regions, advanced technologies have been employed according to the associated wavelength region. In recent years, research and development efforts have been focused on dielectric materials called photonic crystals in which periodic structures totally reflect electromagnetic waves, and that may find various applications including integrated optical circuits, high efficiency laser oscillation, and frequency adjustable filters.
Non-Patent Document 1: W. Wen, L. Zhou, J. Li, W. Ge, C. T. Chen, & P. Sheng; Phys. Rev. Lett. 89, 223901 (2002)
Non-Patent Document 2: V. N. Bolotov, Technical Physics; 45, 1604 (2000)
Non-Patent Document 3: X. Sun and D L. Jaggard; Applied Phys., 70, 2500 (1991)